Move mmap_lock assert function definitions up so that they can be used
by other mmap_lock routines.
Signed-off-by: Suren Baghdasaryan <[email protected]>
---
include/linux/mmap_lock.h | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 96e113e23d04..e49ba91bb1f0 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
#endif /* CONFIG_TRACING */
+static inline void mmap_assert_locked(struct mm_struct *mm)
+{
+ lockdep_assert_held(&mm->mmap_lock);
+ VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
+}
+
+static inline void mmap_assert_write_locked(struct mm_struct *mm)
+{
+ lockdep_assert_held_write(&mm->mmap_lock);
+ VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
+}
+
static inline void mmap_init_lock(struct mm_struct *mm)
{
init_rwsem(&mm->mmap_lock);
@@ -150,18 +162,6 @@ static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
up_read_non_owner(&mm->mmap_lock);
}
-static inline void mmap_assert_locked(struct mm_struct *mm)
-{
- lockdep_assert_held(&mm->mmap_lock);
- VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
-}
-
-static inline void mmap_assert_write_locked(struct mm_struct *mm)
-{
- lockdep_assert_held_write(&mm->mmap_lock);
- VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
-}
-
static inline int mmap_lock_is_contended(struct mm_struct *mm)
{
return rwsem_is_contended(&mm->mmap_lock);
--
2.37.2.789.g6183377224-goog
* Kent Overstreet <[email protected]> [220901 16:24]:
> On Thu, Sep 01, 2022 at 10:34:52AM -0700, Suren Baghdasaryan wrote:
> > Move mmap_lock assert function definitions up so that they can be used
> > by other mmap_lock routines.
> >
> > Signed-off-by: Suren Baghdasaryan <[email protected]>
> > ---
> > include/linux/mmap_lock.h | 24 ++++++++++++------------
> > 1 file changed, 12 insertions(+), 12 deletions(-)
> >
> > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
> > index 96e113e23d04..e49ba91bb1f0 100644
> > --- a/include/linux/mmap_lock.h
> > +++ b/include/linux/mmap_lock.h
> > @@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
> >
> > #endif /* CONFIG_TRACING */
> >
> > +static inline void mmap_assert_locked(struct mm_struct *mm)
> > +{
> > + lockdep_assert_held(&mm->mmap_lock);
> > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
>
> These look redundant to me - maybe there's a reason the VM developers want both,
> but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since
> that's the standard way to write that assertion.
I think this is because the VM_BUG_ON_MM() will give you a lot more
information and BUG_ON().
lockdep_assert_held() does not return a value and is a WARN_ON().
So they are partially redundant.
On Thu, Sep 01, 2022 at 10:34:52AM -0700, Suren Baghdasaryan wrote:
> Move mmap_lock assert function definitions up so that they can be used
> by other mmap_lock routines.
>
> Signed-off-by: Suren Baghdasaryan <[email protected]>
> ---
> include/linux/mmap_lock.h | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
> index 96e113e23d04..e49ba91bb1f0 100644
> --- a/include/linux/mmap_lock.h
> +++ b/include/linux/mmap_lock.h
> @@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
>
> #endif /* CONFIG_TRACING */
>
> +static inline void mmap_assert_locked(struct mm_struct *mm)
> +{
> + lockdep_assert_held(&mm->mmap_lock);
> + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
These look redundant to me - maybe there's a reason the VM developers want both,
but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since
that's the standard way to write that assertion.
On Thu, Sep 1, 2022 at 1:51 PM Liam Howlett <[email protected]> wrote:
>
> * Kent Overstreet <[email protected]> [220901 16:24]:
> > On Thu, Sep 01, 2022 at 10:34:52AM -0700, Suren Baghdasaryan wrote:
> > > Move mmap_lock assert function definitions up so that they can be used
> > > by other mmap_lock routines.
> > >
> > > Signed-off-by: Suren Baghdasaryan <[email protected]>
> > > ---
> > > include/linux/mmap_lock.h | 24 ++++++++++++------------
> > > 1 file changed, 12 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
> > > index 96e113e23d04..e49ba91bb1f0 100644
> > > --- a/include/linux/mmap_lock.h
> > > +++ b/include/linux/mmap_lock.h
> > > @@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
> > >
> > > #endif /* CONFIG_TRACING */
> > >
> > > +static inline void mmap_assert_locked(struct mm_struct *mm)
> > > +{
> > > + lockdep_assert_held(&mm->mmap_lock);
> > > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
> >
> > These look redundant to me - maybe there's a reason the VM developers want both,
> > but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since
> > that's the standard way to write that assertion.
>
> I think this is because the VM_BUG_ON_MM() will give you a lot more
> information and BUG_ON().
>
> lockdep_assert_held() does not return a value and is a WARN_ON().
>
> So they are partially redundant.
Yeah and I do not intend to change the existing functionality in this
patchset. If needed we can post a separate patch removing the
redundancy but from my experience debugging this code, VM_BUG_ON_MM
reports were very useful.
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
>
On 2022-09-01 16:24:09 [-0400], Kent Overstreet wrote:
> > --- a/include/linux/mmap_lock.h
> > +++ b/include/linux/mmap_lock.h
> > @@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
> >
> > #endif /* CONFIG_TRACING */
> >
> > +static inline void mmap_assert_locked(struct mm_struct *mm)
> > +{
> > + lockdep_assert_held(&mm->mmap_lock);
> > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
>
> These look redundant to me - maybe there's a reason the VM developers want both,
> but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since
> that's the standard way to write that assertion.
Exactly. rwsem_is_locked() returns true only if the lock is "locked" not
necessary by the caller. lockdep_assert_held() checks that the lock is
locked by the caller - this is the important part.
Sebastian
On Thu, Sep 1, 2022 at 11:23 PM Sebastian Andrzej Siewior
<[email protected]> wrote:
>
> On 2022-09-01 16:24:09 [-0400], Kent Overstreet wrote:
> > > --- a/include/linux/mmap_lock.h
> > > +++ b/include/linux/mmap_lock.h
> > > @@ -60,6 +60,18 @@ static inline void __mmap_lock_trace_released(struct mm_struct *mm, bool write)
> > >
> > > #endif /* CONFIG_TRACING */
> > >
> > > +static inline void mmap_assert_locked(struct mm_struct *mm)
> > > +{
> > > + lockdep_assert_held(&mm->mmap_lock);
> > > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
> >
> > These look redundant to me - maybe there's a reason the VM developers want both,
> > but I would drop the VM_BUG_ON() and just keep the lockdep_assert_held(), since
> > that's the standard way to write that assertion.
>
> Exactly. rwsem_is_locked() returns true only if the lock is "locked" not
> necessary by the caller. lockdep_assert_held() checks that the lock is
> locked by the caller - this is the important part.
Ok, if at the end of the day there is a consensus that this redundancy
should be removed then I'll do that in a patch separate from this
series. Please note that in this patch I'm not changing these
functions in any way, just moving them.
>
> Sebastian
>
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> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
>